U.S. patent application number 12/375675 was filed with the patent office on 2010-01-14 for lamination shaping apparatus.
Invention is credited to Satoshi Abe, Isao Fuwa, Yoshikazu Higashi, Norio Yoshida.
Application Number | 20100006228 12/375675 |
Document ID | / |
Family ID | 40075150 |
Filed Date | 2010-01-14 |
United States Patent
Application |
20100006228 |
Kind Code |
A1 |
Abe; Satoshi ; et
al. |
January 14, 2010 |
LAMINATION SHAPING APPARATUS
Abstract
A lamination shaping apparatus has a powder layer preparing
means and an optical unit which irradiates a light beam to an
intended portion of a powder layer so as to sinter or melt for
solidifying the portion into a cured layer. Preparation of the
powder layer and curing of the cured layer are repeated to
fabricate a three-dimensional object in which a plurality of the
cured layers are laminated and integrated. The apparatus includes a
fixed base carrying thereon the powder layer and the cured layer,
an elevator frame surrounding a periphery of the fixed base, and
driving means for driving the elevator frame to move vertically.
The powder layer is formed within a space above the base and
surrounded by an interior surface of the elevator fame such that
the powder layer (cured layer) can be stacked on the base with the
base being kept at a fixed position, thereby facilitating to
fabricate a precisely shaped object.
Inventors: |
Abe; Satoshi;
(Moriguchi-shi, JP) ; Higashi; Yoshikazu;
(Moriyama-shi, JP) ; Yoshida; Norio;
(Kitakatsuragi-gun, JP) ; Fuwa; Isao; (Osaka-shi,
JP) |
Correspondence
Address: |
Cheng Law Group, PLLC
1100 17th Street, N.W., Suite 503
Washington
DC
20036
US
|
Family ID: |
40075150 |
Appl. No.: |
12/375675 |
Filed: |
May 30, 2008 |
PCT Filed: |
May 30, 2008 |
PCT NO: |
PCT/JP2008/060048 |
371 Date: |
February 20, 2009 |
Current U.S.
Class: |
156/356 ;
156/379.6 |
Current CPC
Class: |
B29C 64/371 20170801;
B22F 12/00 20210101; B22F 2999/00 20130101; B33Y 30/00 20141201;
B29C 64/188 20170801; B29C 64/268 20170801; B29C 2793/009 20130101;
B22F 10/70 20210101; B29C 64/25 20170801; Y02P 10/25 20151101; B22F
10/10 20210101; B29C 64/153 20170801; B22F 2999/00 20130101; B22F
10/20 20210101; B22F 3/003 20130101; B22F 2999/00 20130101; B22F
10/20 20210101; B22F 3/003 20130101 |
Class at
Publication: |
156/356 ;
156/379.6 |
International
Class: |
B32B 37/00 20060101
B32B037/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2007 |
JP |
2007-144014 |
Claims
1. A lamination shaping apparatus comprising: a powder layer
preparing means configured to prepare a powder layer of inorganic
or organic powder material; and an optical unit configured to
irradiate a light beam to an intended portion of said powder layer
in order to sinter or melt for solidifying the portion into a cured
layer such that the preparation of said powder layer and the
forming of said cured layer are repeated to fabricate a
three-dimensional object in which a plurality of said cured layers
are laminated and integrated; wherein said apparatus includes a
fixed base carrying thereon said powder layer and said cured layer;
an elevator frame configured to surround a periphery of said fixed
base and to be vertically movable relative to said fixed base,
thereby defining thereabove a space which is surrounded by an
interior surface of said elevator frame to prepare said powder
layer; and an elevator driving means which drives said elevator
frame to move vertically.
2. A lamination shaping apparatus comprising: a powder layer
preparing means configured to prepare a powder layer of inorganic
or organic powder; an optical unit configured to irradiate a light
beam to an intended portion of said powder layer in order to sinter
or melt for solidifying the portion into a cured layer such that
the preparation of said powder layer and the forming of said cured
layer are repeated to fabricate a three-dimensional object in which
a plurality of said cured layers are laminated and integrated; a
milling unit provided to grind a surface of a precursor of said
three-dimensional object being fabricated, wherein said apparatus
includes a fixed base carrying thereon said powder layer and said
cured layer; an elevator frame configured to surround a periphery
of said fixed base and to be vertically movable relative to said
fixed base, thereby defining thereabove a space which is surrounded
by an interior surface of said elevator frame to prepare said
powder layer, and an elevator driving means which drives said
elevator frame to move vertically, said milling unit being in the
form of a numerical control machine having a table which is
controllable at least with respect to three axes and is fixed to
said base.
3. A lamination shaping apparatus as set forth in claim 1 or 2,
wherein said powder layer preparing means includes a slide plate
which is slidable on a top face of said elevator frame and has a
powder supply port for feeding said powder into said space formed
on said base and surrounded by said elevator frame.
4. A lamination shaping apparatus as set forth in claim 3, wherein
said powder supply port is dimensioned to have a width which is
perpendicular to a sliding direction of said slide plate, the width
of said powder supply port being greater than a corresponding width
of said base.
5. A lamination shaping apparatus as set forth in claim 3, wherein
said slide plate is provided with a member for enhancing a bulk
density of said powder.
6. A lamination shaping apparatus as set forth in claim 3, wherein
said slide plate is provided with a member for smoothening the
surface of said powder layer.
7. A lamination shaping apparatus as set forth in claim 1 or 2,
further including: a mask frame which is disposed on said elevator
frame to have an open bottom and a window in its top opening for
passing therethrough said light beam; and an atmospheric gas
supplying means for supplying an atmospheric gas within said mask
frame.
8. A lamination shaping apparatus as set forth in claim 7, wherein
said mask frame is provided with a whirl flow forming means for
supplying said atmospheric gas in the form of a whirl flow into
within said mask frame.
9. A lamination shaping apparatus as set forth in claim 7, further
including: an oxygen concentration meter for measuring an oxygen
concentration within an interior space of said mask frame, said
atmospheric gas supplying means being configured to supply said
atmospheric gas according to an output of said oxygen concentration
meter.
10. A lamination shaping apparatus as set forth in claim 7, further
including: a piston configured to move vertically within said mask
frame for supplying and discharging the atmospheric gas.
11. A lamination shaping apparatus as set forth in claim 7, wherein
said window is in the form of a f.cndot..theta. lens.
12. A lamination shaping apparatus as set forth in claim 7, further
including a cleaning means configured to clean the interior surface
of said mask frame including the interior surface of said
window.
13. A lamination shaping apparatus as set forth in claim 12,
wherein said cleaning means comprises a cleaning member which is
formed on said elevator frame to be vertically movable and
rotatable within the mask frame for clearing the interior surface
of said mask frame including the interior surface of said
window.
14. A lamination shaping apparatus as set forth in claim 12,
wherein a plurality of said mask frames are provided to be slidable
on the top face of said elevator frame such that when one of said
mask frames is positioned on said base, the other mask frame comes
into a position where it is cleaned by said cleaning means.
15. A lamination shaping apparatus as set forth in claim 7, wherein
said optical unit is disposed on the side of said mask frame.
16. A lamination shaping apparatus as set forth in claim 1 or 2,
further including: a mark target provided on the top face of said
elevator frame for providing a marking thereon by the light beam
from said optical unit, and a measuring unit configured to measure
said marking on said mark target to obtain a compensation data with
regard to an irradiation spot intended by the light beam from said
optical unit.
17. A lamination shaping apparatus as set forth in claim 1 or 2,
further including: a power meter disposed on the top face of said
elevation frame and configured to measure a power of the light beam
from said optical unit.
18. A lamination shaping apparatus as set forth in claim 1 or 2,
further including: a mask frame being disposed on said elevator
frame, having an open bottom, and having in its top opening with a
window for passing therethrough said light beam; an atmospheric gas
supplying means for supplying an atmospheric gas within said mask
frame; and a slide plate which is slidable on the top face of said
elevation frame and which is provided with said powder layer
preparing means, said mask frame being formed as a portion of said
slide plate.
19. A lamination shaping apparatus as set forth in claim 1 or 2,
wherein said elevation frame is configured to surround an outer
periphery of each of said plural bases and be vertically movable
relative to each said base, a slide plate being provided to be
slidable on the top face of said elevation fame, said powder layer
preparing means being provided on said slide plate to prepare said
powder layer on or above the plural bases selectively by the
sliding movement of said slide plate.
20. A lamination shaping apparatus as set forth in claim 19,
wherein said slide plate is formed with a milling opening for
passing therethrough a tool of said milling unit.
21. A lamination shaping apparatus as set forth in claim 18,
wherein said slide plate is provided with a suction unit which
sucks uncured powder on said base for removal.
22. A lamination shaping apparatus as set forth in claim 18,
wherein said slide plate is configured to rotate in a sliding
relation with the top face of said elevation frame.
23. A lamination shaping apparatus as set forth in claim 18,
wherein said optical unit is disposed to have a variable height
position relative to a plane irradiated by the light beam.
24. A lamination shaping apparatus as set forth in claim 19,
wherein said slide plate is provided with a suction unit which
sucks uncured powder on said base for removal.
25. A lamination shaping apparatus as set forth in claim 19,
wherein said slide plate is configured to rotate in a sliding
relation with the top face of said elevation frame.
26. A lamination shaping apparatus as set forth in claim 19,
wherein said optical unit is disposed to have a variable height
position relative to a plane irradiated by the light beam.
Description
TECHNICAL FIELD
[0001] The present invention relates to a lamination shaping
apparatus for fabricating a three-dimensional lamination object
with the use of a light beam irradiated to sinter or melt powder
material for solidification thereof.
BACKGROUND ART
[0002] There is already proposed a process of fabricating a
lamination object known as a selective powder sintering lamination.
The process includes a step of forming a powder layer of inorganic
or organic powder, and a step of irradiating a light beam to an
intended portion of the powder layer to sinter or melt for
solidifying it into a cured layer, these steps being repeated to
fabricate the object in which a plurality of the cured layer are
laminated and integrated. Japanese patent publication JP2002-115004
A (patent document 1) discloses, in addition to the above, to
provide a step of grinding a surface of a precursor of the object
between the repeated curing steps of forming the curing layers in
order to give a smooth finish to the object of various shape at a
low cost.
[0003] However, the above prior art sees a drawback as to accuracy
of the laminated object. That is, in order to successively forming
the thin powder layers, as shown in FIG. 22, a shaping section is
composed of a shaping stage 61, an elevation mechanism 62 for
elevating the shaping stage 61, and a shaping frame 63 surrounding
the shaping stage 61. Further, a powder supplying section is
composed of a tank 65, an elevation mechanism 66 and an elevation
table 67 for lifting the powder material in the tank, a supplier
blade 68 for feeding the powder material from the top of the tank
onto the shaping stage 61 and smoothening the powder material.
[0004] With this arrangement, the powder layer on the shaping stage
61 is sintered or melted at a predetermined portion to be
solidified into the cured layer, and a subsequent powder layer is
formed by lowering the shaping stage 61 and lifting the elevation
table 67 by one step followed by moving the supplier blade 68.
However, since the shaping stage 61 carrying thereon the object is
made movable, the precursor of the object is likely to suffer from
a minute positional fluctuation during the course of irradiating
the light beam to sinter or melt for solidification, or using a
milling machine for grinding, which makes it difficult to precisely
fabricate the object having the order of micrometers.
[0005] Further, the elevation mechanism 62 and 66 for elevating the
shaping stage 61 and the elevation table 67 have to be disposed
below the stage 61 and table 67. With this result, the shaping
section has a total height of H more than doubled an elevation
range H1 of the shaping stage 61 (and elevation table 67), making
it difficult to reduce the total height of the apparatus. In the
figure, H2 indicates a driving range of the elevation means
62(66).
[Patent document 1] JP 2002-115004 A
DISCLOSURE OF THE INVENTION
[Problem to be Solved by the Invention]
[0006] The present invention has been achieved in view of the above
drawbacks and has a problem of providing a lamination shaping
apparatus which is capable of fabricating a highly precise
lamination object, yet with a compact arrangement.
[Means for Solving the Problem]
[0007] The lamination shaping apparatus in accordance with the
present invention is characterized in the first instance to include
a powder layer preparing means configured to prepare a powder layer
of inorganic or organic powder material, and an optical unit
configured to irradiate a light beam to an intended portion of the
powder layer to sinter or melt for solidifying the portion into a
cured layer such that the preparation of the powder layer and the
curing of the cured layer are repeated to fabricate a
three-dimensional object in which a plurality of the cured layers
are laminated and integrated. The apparatus further includes a
fixed base carrying thereon the powder layer and the cured layer,
an elevator frame configured to surround a periphery of the fixed
base and to be vertically movable relative to the fixed base,
thereby defining thereabove a space which is surrounded by an
interior surface of the elevator frame to prepare the powder layer;
and an elevator driving means which drives the elevator frame to
move vertically. The lamination shaping apparatus in accordance
with the present invention is characterized in the second instance
to include a powder layer preparing means configured to prepare a
powder layer of inorganic or organic powder material, an optical
unit configured to irradiate a light beam to an intended portion of
the powder layer in order to sinter or melt for solidifying the
portion into a cured layer such that the preparation of the powder
layer and the curing of the cured layer are repeated to fabricate a
three-dimensional object in which a plurality of the cured layers
are laminated and integrated, and a milling unit provided to grind
a surface of a precursor of the three-dimensional object being
fabricated, wherein the apparatus further includes a fixed base
carrying thereon the powder layer and the cured layer, an elevator
frame configured to surround a periphery of the fixed base and to
be vertically movable relative to the fixed base, and an elevator
driving means which drives the elevator frame to move vertically.
The milling unit being in the form of a numerical control machine
having a table which is controllable at least in three axes and is
fixed to the base such that the powder layer is prepared within a
space disposed above the base and surrounded by an interior surface
of the elevator frame.
[0008] Accordingly, the powder layer (cured layer) can be stacked
on the base with the base kept stationary, enabling to fabricate a
highly precise object.
[0009] When the powder layer preparing means is configured to
include a slide plate which is slidable on a top face of the
elevator frame and has a powder supply port for feeding the powder
into the space formed on the base and surrounded by the elevator
frame, it is easily to be made into a compact structure.
[0010] When the powder supply port is dimensioned to have a width
which is perpendicular to a sliding direction of said slide plate,
and which is greater than a corresponding width of the base, the
powder can be supplied uniformly.
[0011] The slide plate may be preferred to include a member for
enhancing a bulk density of said powder in order to increase
post-sintered or melt-solidified density.
[0012] The slide plate may be provided with a member for
smoothening the surface of the powder layer so as to give
advantages of preventing wear-deterioration, supplying the powder
stably, and reducing surface roughness of the cured layer.
[0013] Further, the apparatus is preferred to include a mask frame
which is disposed on the elevator frame to have an open bottom and
a window in its top opening for passing therethrough the light
beam, and an atmospheric gas supplying means for supplying an
atmospheric gas within the mask frame. With this arrangement, it is
possible to restrain the amount of the atmospheric gas while
avoiding oxidization of the cured layer.
[0014] The mask frame may be provided with a whirl flow forming
means for supplying said atmospheric gas in the form of a whirl
flow into within said mask frame, enabling to efficiently charging
the atmospheric gas.
[0015] The apparatus may further include an oxygen concentration
meter for measuring an oxygen concentration within an interior
space of said mask frame. In this version, the atmospheric gas
supplying means is configured to supply the atmospheric gas
according to an output of said oxygen concentration meter in order
to further restrain the amount of the atmospheric gas.
[0016] The apparatus may includes a piston which is configured to
move vertically within the mask frame for supplying and exhausting
the atmospheric gas, thereby making prompt supply and discharge of
the atmospheric gas.
[0017] When the window is in the form of a f.cndot..theta. lens, it
is possible to make accurate sintering or melt-solidification.
[0018] The apparatus is preferred to include a cleaning means
configured to clean the interior surface of said mask frame
including the interior face of said window so as to remove dirt due
to a fume generating at the sintering for successful sintering. The
cleaning means may be composed of a cleaning member which is formed
on the elevator frame to be vertically movable and rotatable within
the mask frame.
[0019] Also, a plurality of the mask frames may be provided to be
slidable on the top face of the elevator frame such that when one
of the mask frames is positioned on the base, the other mask frame
comes into a position where it is cleaned by the cleaning means.
Whereby, it is possible to simultaneously make the sintering and
cleaning for reducing an increase of fabrication time due to the
cleaning operation.
[0020] The optical unit may be disposed on the side of the mask
frame.
[0021] The apparatus may include a mark target provided on the top
face of the elevator frame for providing a marking thereon by the
light beam from the optical unit, and a measuring unit configured
to measure the marking on the mark target to obtain a compensation
data for an irradiation spot intended by the light beam from the
optical unit. This arrangement enables to enhance the accuracy of
irradiating the light beam for sintering or
melt-solidification.
[0022] When a power meter is disposed on the top face of the
elevation frame so as to measure a power of the light beam from the
optical unit, it is easy to make an accurate sintering or
melt-solidification with a moderate power, and also to indicate a
proper cleaning time when equipped with the cleaning means.
[0023] The lamination shaping apparatus of claim 1 or 2 is
preferred to include a mask frame which is disposed on the elevator
frame to have an open bottom, and a window in its top opening for
passing therethrough the light beam, an atmospheric gas supplying
means for supplying an atmospheric gas within said mask frame, and
a slide plate which is slidable on the top face of the elevation
frame and is provided with the powder layer preparing means,
wherein the mask frame is formed as a portion of the slide plate.
With this arrangement, the sliding of the slide plate makes the
preparation of the powder layer as well as the sintering or
melt-solidification under an inert atmospheric condition for
efficient fabrication of the lamination object.
[0024] Still further, the elevation frame may be configured to
surround an outer periphery of each of the plural bases and to be
vertically movable relative to each of the bases. In this version,
a slide plate is provided to be slidable on the top face of the
elevation fame, while the powder layer preparing means is provided
on the slide plate to prepare the powder layer on or above the
plural bases selectively by the sliding movement of the slide
plate. With this arrangement, the vertical movement of the single
elevation frame is cooperative with the sliding movement of the
slide plate to prepare the powder layers respectively on the plural
bases.
[0025] The slide plate may be formed with a milling opening for
passing therethrough a tool of the milling unit, such that the
sliding movement of the slide plate can alone make a switching
among the powder supply, the sintering or melt-solidification, and
the grinding.
[0026] When the slide plate is provided with a suction unit for
sucking uncured powder on the base for removal, it is easy to
prevent the uncured powder from hindering the grinding and lowering
the grinding accuracy.
[0027] When the slide plate is configured to rotate in a sliding
relation with the top face of the elevation frame, the apparatus
can be made compact even in the presence of various components
incorporated in the slide plate.
[0028] When the optical unit is disposed to have a variable height
position relative to a plane irradiated by the light beam, the
irradiation of the light bean can be made in well conformity with
the shaping rate or accuracy.
[Effect of the Invention]
[0029] The present invention enables to stack the powder layers
(cured layers) on the base while keeping the base stationary, thus
eliminating a factor of degrading the accuracy of the object being
formed on the base and therefore assuring easy fabrication of
highly precise lamination object. In a version in which the milling
unit is employed to grind the surface of a precursor of the
laminated object between the repeated steps of preparing the powder
layer and the curing it into the cured layer, it is possible to
avoid possible fluctuation of the laminated object at the time of
grinding, thereby also assuring easy fabrication of highly precise
lamination object.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a schematic section illustrating an embodiment of
the present invention;
[0031] FIGS. 2(a) and (b) are schematic views respectively
illustrating a manner of attaching an optical unit of the above
embodiment;
[0032] FIGS. 3(a), (b), and (c) are plan and schematic sectional
views illustrating a powder supply section of the above
embodiment;
[0033] FIG. 4 is a schematic sectional view explaining a
modification of the powder supply section utilized in the above
embodiment;
[0034] FIGS. 5(a), (b), (c) are respectively plan view of the above
powder supply section, a schematic plan view of still another
modification of the powder supply section, and a schematic plan
view of a further modification of the powder supply section,
respectively;
[0035] FIG. 6 is a schematic plan view of a still further
modification of the powder supply section;
[0036] FIGS. 7(a) and (b) are schematic sectional views of more
further modification of the powder supply section;
[0037] FIG. 8 is a schematic sectional view of a mask frame
utilized to develop an inert atmosphere;
[0038] FIGS. 9(a) and (b) are a horizontal sectional view and a
schematic sectional view of a modification of the mask frame;
[0039] FIG. 10 is a schematic sectional view of a cleaning
member;
[0040] FIGS. 11(a) and (b) are schematic sectional views
illustrating an instance of providing two sets of the cleaning
members;
[0041] FIGS. 12(a) and (b) are schematic sectional views
illustrating a configuration for positional compensation of an
irradiation spot by the light beam;
[0042] FIGS. 13(a) and (b) are schematic sectional views
illustrating a configuration for measurement of a power of the
light beam;
[0043] FIGS. 14(a), (b), and (c) are a plan view, schematic a
vertical section, and a schematic horizontal section illustrating
another embodiment of the present invention;
[0044] FIGS. 15(a) and (b) are a plan view, and a schematic
vertical section illustrating a further embodiment;
[0045] FIG. 16 is a schematic section illustrating another
arrangement of disposing the optical unit;
[0046] FIGS. 17(a), (b), and (c) are a horizontal section and
schematic sections respectively of a slide plate equipped with a
powder suction mechanism;
[0047] FIG. 18 is a schematic section illustrating a modification
in which the optical unit is made removable;
[0048] FIG. 19 is a schematic section illustrating a modification
in which the powder supply port is provided with a cover;
[0049] FIGS. 20(a) and (b) are perspective views illustrating
another modification in which the powder supply port is provided
with a cover;
[0050] FIG. 21 is a schematic section illustrating a modification
in which the elevator frame is provided with a discharge port;
and
[0051] FIGS. 22(a) and (b) are partly cut-away perspective view and
a partial sectional view illustrating a prior art.
EXPLANATION OF THE REFERENCE NUMERALS
[0052] 1: shaping unit [0053] 2: optical unit [0054] 3: milling
unit [0055] 8: powder [0056] 9: cured layer [0057] 10: shaping
section [0058] 11: base [0059] 12: elevator frame [0060] 15: powder
supply section [0061] L: light beam
BEST MODE FOR CARRYING OUT THE INVENTION
[0062] The present invention is now explained with reference to the
attached drawings. FIG. 1 illustrates a lamination shaping
apparatus which includes a shaping unit 1 composed of a shaping
section 10 and a powder supply section 15 disposed on the shaping
section 10, an optical unit 2 irradiating a light beam L to the
shaping section 10, and a milling unit 3 for grinding.
[0063] The milling unit 3 is a numerically controlled machine tool
having a table (machining table) 30 and a headstock 31 controllable
with respect to at least 3-axis. The headstock 31 has a spindle
head 32 equipped with an end mill 33 for grinding, while the
shaping unit 1 is disposed on the table 30 of the milling unit 3. A
base 11 is fixed to the table 30 to form thereon a lamination
object. The optical unit 2 is attached to the headstock 31. In the
illustrated embodiment, the spindle head 32 is movable along X-axis
and Z-axis, while the table 30 is movable along Y-axis.
[0064] The shaping section 10 of the shaping unit 1 is provided to
form the lamination object on the base 11 fixed to the table 30, as
explained in the above, and is provided with an elevator frame 12
which surrounds the periphery of the base 10 and is driven to move
up and down by an elevator driving means in the form of a linear
driving mechanism. The elevator frame 12 has a sufficient thickness
at a portion around the base 11 such that a space of sufficient
height is formed on the base within the confined of the elevator
frame when the elevator frame 12 is raised relative to the base
11.
[0065] The powder supply section 15 is composed of a powder
supplier (not shown) for supplying the powder on to the elevator
frame 12, a supplier blade 16 disposed above the top face of the
elevator frame 12, and a driving section 17 for horizontally
driving the supplier blade 16.
[0066] Although not limited to a particular kind, the powder
material 8 may be inorganic (metal or ceramic) powder or organic
(plastic) powder that can be solidified into a cured layer by
exposure to the light beam irradiated from the optical unit 2. In
the illustrated example, an iron powder having an average particle
size of 20 .mu.m is utilized as the powder material.
[0067] The milling unit 3 has an end-mill 33 of a numerical
controlled machining tool, especially a cutting tool, as a
replaceable machining center. The end-mill 33 is chiefly selected
as a ball end-mill with double carbide blades, and may be selected
from a square end-mill, radius end-mill, or drill in accordance
with to a particular shape or purpose.
[0068] The optical unit 2, which irradiates the light beam L for
sintering the powder 8, includes a light source 21 composed of a
laser oscillator, a collecting lens, and a scan mechanism 22
composed of a galvanometer for deflecting the light beam L to
direct it to the intended points or portions. In the illustrated
embodiment, the scan mechanism 22 has its portion fixed to a side
of the spindle head 32 with the scan mechanism 22 being connected
to the light source 21 by way of an optical fiber 23. The light
source 21 is realized by a carbon dioxide gas laser (500 W output
power) or Nd:YAG laser (500 W output power) when the iron powder is
utilized.
[0069] The scan mechanism 22 (optical unit 2) may be detachable to
a mount 310 on the side of the spindle head 32 as shown in FIG.
2(a), or may be attached to the spindle head 32 by means of a
collet chuck instead of the end-mill 33, as shown in FIG. 2(b). In
the latter case, the spindle head 32 can be located at the same
position irrespective of irradiating the light beam L or using the
end-mill 33, thereby minimizing the overall travelling range of the
spindle head 32 as compared to the case in which the optical unit 2
is disposed on the side of the headstock 31, therefore enabling to
fabricate the object of relatively large volume. In addition, the
absence of the optical unit 2 on the headstock 31 ensures to make
grinding by use of the end-mill 32 free from being interfered with
the optical fiber 23, and therefore with a reduced influence of
vibrations.
[0070] When fabricating the lamination object with the above
lamination shaping apparatus, the powder 8 is supplied onto the top
of the elevator frame 12. While keeping the top of the elevator
frame 12 a level slightly higher than a shaping plate fixed on the
base 11, the blade 16 is driven to move horizontally to supply the
powder 8 onto the base 11 and smoothen the same so as to form the
first powder layer, followed by irradiating the light beam L from
the optical unit 2 located above the shaping section 10 to a
portion intended to be cured, thereby sintering the powder 8 to
form the curd layer.
[0071] Subsequently, the elevator frame 12 is lifted by a
predetermined extent so that the supply and the smoothing of the
powder 8 are made to prepare the second powder layer on the first
powder layer (and the cured layer). Then, the light beam L is
irradiated to a portion intended to be cured of the second powder
layer to cure the powder, forming the next cured layer integrated
with the lower cured layer.
[0072] The steps of lifting the elevator frame 12 to prepare a
fresh powder layer and irradiating the light beam L to the
predetermined portion of the layer to form the cured layer are
repeated to fabricate the three-dimensional object 9 of intended
shape as a lamination object on the shaping plate on top of the
base 11. The power layer is preferred to have a thickness of 0.05
mm when the resulting object is utilized as a molding die.
[0073] An irradiation path (hatching path) of the light beam L is
prepared beforehand from a three-dimensional CAD data of the
lamination object. That is, an STL (Standard Triangulation
Language) data obtained from a three-dimensional CAD model is
sliced at a constant pitch (0.05 mm pitch when the thickness of the
powder layer is 0.05 mm) to give a sectional contour data of each
section based on which the irradiation path is prepared. In this
connection, the irradiation of the light beam L is made to sinter
the outermost surface of the lamination object at a high density
(below 5% of porosity) and sinter the interior at a low density. In
other words, the sectional contour data is divided into a
peripheral portion and an inside portion such that the irradiation
of the light beam L is made to sinter the peripheral portion at a
condition of melting the powder almost completely to give the high
density, while sintering the inside portion at a condition of
leaving a porous structure, whereby enabling fast manufacturing of
the object with accurately contoured surface.
[0074] While the steps of preparing the powder layer and the
forming of the cured layer by irradiation of the light beam L are
repeated, the total thickness of the cured layers reaches to a
predetermine value determined by a tool length or the like of the
end-mill 33 of the milling unit 3. At this condition, the end-mill
33 is positioned above the shaping section 10 to grind the surface
(chiefly the upper side face) of a precursor of the object 9 being
made.
[0075] The grinding by use of the milling unit 3 removes a residual
cured portion resulting from the powder adhered to the object 9,
thus exposing the high density portion at the outermost surface of
the object. Upon finishing of the grinding operation, the
preparation of the powder layer and the sintering are repeated.
[0076] A grinding work path by the milling unit 3 is determined
beforehand from the three-dimensional CAD data as in the case of
the irradiation path of the light beam L. Although the contour line
processing is applied to determine the grinding work path, there is
no need to be in exact correspondence to the lamination pitch in
the Z-direction (vertical direction) at the sintering, and the
Z-direction pitch can be set to be shorter with the reducing
inclination angle of the object for obtaining more smooth surface
finish.
[0077] FIG. 4 illustrates a modification of the power supply
section 15 which is configured to have a slide plate 18 which is
slidable on the top face of the elevator frame 12 and is provided
with a vertically extending powder supply port 19. When the powder
supply port 19 is in a position on the elevator frame 12 not above
the base 11, the powder is fed from the powder supplier (not shown)
into the powder supply port 19, after which the slide plate 18 is
slid across the base 11 to supply the powder on the base and at the
same time to smooth the powder. The sintering is made by
irradiating the light beam L at a condition where the powder supply
port 19 is positioned above the base 11 to direct the light beam
through the powder supply port, or at a condition where the slide
plate 18 is receded from above the base 11.
[0078] In this connection, the powder supply port 19 has a width (a
dimension along a direction perpendicular to the sliding direction
of the slide plate 18) which is greater than the corresponding
width of the base 11, as shown in FIG. 5(a), to supply the powder
evenly over the entire portion on the base 11. The powder supply
port 19 is not necessarily square, and may be rectangular,
circular, ellipsoid or any other shape to supply the powder 8 to
the entire portion on the base 11.
[0079] Further, as shown in FIG. 5(b), the slide plate 18 may be
provided in its interior with a rotary plate 190 which is rotatable
about a vertical axis and is formed with a like powder supply port
19. In this modification, the rotation of the rotary plate 190 can
vary the width of the powder supply port 19 with regard to the
above direction.
[0080] As shown in FIG. 5(c), the inner wall of the powder supply
port 19 is preferably finished with irregularities for effectively
avoiding the powder 8 from aggregating on one width end within the
powder supply port 19. Further, a collector may be formed either on
the side of the slide plate 18 or the elevator frame 12 in order to
avoid an occurrence in which residual powder would be hindrance to
the sliding movement of the slide plate 18.
[0081] With the arrangement in which the sliding movement of the
slide plate 18 having the powder supply port 19 is used for
supplying the powder 8 into the shaping space confined by the
elevator frame 12 on the base 11, it is possible to place a weight
81 on the powder within the powder supply port 19 for pressuring
the same, and/or add a vibration generator 82 to vibrate the powder
8, thereby enhancing the bulk density of the powder 8 being
supplied to the base 11 and therefore increasing the density of the
powder layer for obtaining the object of high sintering
density.
[0082] Although the slide plate 18 itself functions as a member of
smoothening the powder layer on the base 11 in the above
illustrated embodiment, a blade 16 for smoothing the powder 8 may
be provided on both (or either one) of the opposite sides (or
either one of the o) of the powder supply port 19 of the slide
plate 18 with respect to its sliding direction, as shown in FIG. 7.
This is advantageous particularly in case where the slide plate 18
is made of a light metal for lightweight purpose. The blade 16 is
preferably made of steel or ceramics in consideration of that a
hard projection possible resulting from abnormal sintering may be
present on the surface of the powder being smoothed by the blade
16.
[0083] Further, in order to successfully remove the projection, the
slide plate 18 may be provided with a rotary cutter 83 of which
lower end is held in level with the lower surface of the slide
plate 18 so as to cut away the projection by the rotary cutter 83.
The rotary cutter 83 may be driven by a separately mounted motor or
by a mechanism that uses the sliding movement of the slide plate 18
to rotate the rotary cutter 83, for instance, a rack-and-pinion
mechanism.
[0084] When irradiating the light beam L onto the powder layer for
sintering with the powder being exposed to the atmosphere,
oxidization may occur depending upon the kind of the powder
material, failing to sinter the powder neatly. In order to avoid
this insufficiency, the light beam L is irradiated within an inert
atmosphere with the use of a mask frame 40 disposed on the elevator
frame 12, as shown in FIG. 8. The mask frame 40 has a bottom
opening which is larger than the upper surface area of the base 11
and has its top closed by a window 41 such that the light beam L is
irradiated through the window 41 in a condition where an inert
atmospheric gas (for instance, nitrogen or argon) is filled in the
space surrounded by the mask frame 40. Numeral 45 designate an
atmospheric gas generator or tank, 46 designates a dust collector
for collecting fume generating at the sintering, 47 designates a
gas charge port, and 48 designates a gas discharge port. Since the
atmospheric gas is required to fill only the small space surrounded
by the mask frame 40 on the base 11, it is possible to reduce the
time for charging and discharging the atmospheric gas and the
amount of the atmospheric gas.
[0085] For the purpose of reducing the amount of the atmospheric
gas, it is possible to provide an oxygen meter 49 for measurement
of oxygen concentration in the space of the mask frame 40 so as to
supply the atmospheric gas only when the oxygen concentration
becomes higher than a predetermined oxygen concentration.
[0086] For the purpose of enhancing transmissivity of the light
beam L, the window 41 may be made of quartz glass when using the
light beam L of YAG laser, and of zinc selenide when using the
light beam L of CO.sub.2 laser. When the window 41 is configured to
function as a f.theta. lens rather than in the form of a parallel
plate, the light beam L focus a spot of constant diameter on the
sintering surface for precise sintering. Although a dynamic
focusing lens may be utilized to give the spot of constant
diameter, such lens is required to be mounted on the optical unit
as an additional part, leading to a problem in an increased bulk
and weight of the optical unit 2.
[0087] The mask frame 40 may be provided as a slide plate 18
slidable on the top face of the elevator frame 12 so as to be
easily movable between a position at which the preparation of the
powder layer and the grinding are made and a position at which the
sintering is made by the light beam irradiation.
[0088] In view of the time required for charging and discharging of
the atmospheric gas, ventilation efficiency of the gas, and
anti-fouling requirement to the window 41, the gas charge port 47
and the gas discharge port 48 of the mask frame 40 are preferred to
direct the atmospheric gas obliquely downwards to the interior
space of the mask frame 40 along the inner periphery thereof, as
shown in FIG. 9, so that the atmospheric gas is caused to flow in a
swirling fashion downwards within the interior space.
[0089] To deal with a problem that the window 41 becomes smudged by
the fume during the extended time of use and suffers from resultant
lowering of transmissivity to the light beam L, the elevator frame
12 is preferred to incorporate a cleaning mechanism for cleaning
the window 41. One example of the cleaning mechanism is shown in
FIG. 10, in which a cleaning member 51 is disposed within an
opening extending vertically through the elevator frame 12 and is
driven by a vertical movement cylinder 53 to move up and down and
is also driven by a motor to rotate. The cleaning member 51 is
formed on its surface with a clearing paper or unwoven fabric and
is provided with a spout for dispensing a cleaning agent
(pressurized air, or water) so as to clean the interior surface of
the window 41 and clean and wipe out the dirt on the interior wall
of the mask frame 40. The vertical movement cylinder 53 is set on
the table 53 such that the cleaning member 51 makes a vertical
movement inclusive of that of the elevator frame 12.
[0090] It is possible to use a plurality of the mask frames 40
forming the inert atmospheric environment, or to use the mask frame
40 having a plurality of windows 41, as shown in FIG. 11, such that
one of the windows 41 is positioned above the cleaning mechanism
when the other window 41 is located above the base 11. In this
instance, the sintering and the cleaning are made simultaneously to
eliminate a waiting time for the cleaning and therefore shorten the
fabrication time of the lamination object.
[0091] The cleaning member 51 may be in the form of a piston which
effects a forced charging and discharging of the atmospheric gas
into and out of the mask frame 40. The cleaning member 51
discharges the atmospheric gas out of the interior space of the
mask frame 40 when being lifted, and sucks the atmospheric gas into
the interior space of the mask frame 40 when being lowered. In this
connection, the gas charge port 47 and the gas discharge port 48
are each provided with a valve that is interlocked with the
cleaning member (piston) 51 to open and close.
[0092] FIG. 12 illustrates an apparatus in which the elevator frame
12 is provided with a mark target 55 to which the light beam L is
irradiated for marking, and an irradiation spot measuring unit 25
is provided for measurement of the spot of the marking on the mark
target 55. The light beam L is irradiated to a predetermined spot
(s) to give the marking of crossed lines or the like, as shown in
FIG. 12(a), then the irradiation spot measuring unit 25 (image
element thereof) takes an image of the marking and makes an image
processing to measure the position of the marking, as shown in FIG.
12(b). Upon recognition of an error in the position of the marking,
it is made to correct the rotation angle of the galvanometer mirror
of the optical unit 2, thereby keeping to irradiate the light beam
L to the spot at high accuracy. Especially, with the above
arrangement, it is easy to correct the irradiation spot by the
light beam L during the fabrication of the lamination object, which
is advantageous for highly precise sintering,
[0093] FIG. 13 illustrates an apparatus in which a power meter 56
is disposed on the elevator frame 12 for measuring a power of the
light beam L. An attenuation factor of the light beam L indicative
of the smudging extent of the window 41 is obtained from a
difference between the outputs of the power meter 56 when receiving
the light beam L through the window 41 of the mask frame and when
receiving the light beam L directly with the mask frame 56 away
from the power meter 56. Accordingly, a time of cleaning the window
41 can be easily and properly determined to enhance fabrication
efficiency as well as to give constantly successful sintering.
[0094] The mask frame 40 and the powder supply section 15 may be
formed on the side of the single slide plate 18, as shown in FIG.
14. The slide plate 18, which is linearly slidable on the top face
of the elevator frame 12, is provided at its lengthwise end with
the powder supply port 19, and defines at its opposite lengthwise
end the mask frame 40 with the window 41. The slide plate 18 is
driven to slide on the top face of the elevator frame 12 by a
linear driver such as a linear motor disposed on the side of the
elevator frame 12.
[0095] The slide plate 18 is moved from the position as shown in
FIG. 14 to a leftward position in FIG. 14 for preparing a fresh
powder layer on the base 11 followed by the light beam L being
irradiated through the window 41 to the powder layer for sintering.
When grinding the object 9 by the milling unit 3, the slide plate
18 is caused to return to the illustrated position to expose the
base 11.
[0096] FIG. 15 illustrates a modification in which the slide plate
18 is in the form of a disc which is driven by a motor 58 to rotate
about its axis in a sliding relation with the top face of the
elevator frame 12. The slide plate 18, which defines itself the
power supply section 15 having the powder supply port 19 as well as
the mask frame 40 having the window 41, is formed with a milling
opening 39 that extends vertically for use during the grinding
processing with the milling unit 3.
[0097] By rotating the slide plate 18, the powder supply section
15, the mask frame 40, and the milling opening 39 each formed in a
peripheral portion of the slide plate 18 are successively and
interchangeably positioned above the base 11. In the illustrated
instance, a plurality of minute holes 38 are formed in the portion
between mask frame 40 and the milling opening 39 for sucking the
powder (or swarf occurred in the previous grinding), enabling to
make the subsequent grinding without the presence of the uncured
powder and therefore preventing the object being impaired by the
uncured powder or avoiding the mixing of the swarf into the
subsequently prepared powder layer.
[0098] FIG. 17 illustrates a modification in which the slide plate
18 integrated with the mask frame 40 is formed with the powder
supply port 19 and a powder sucking mechanism. The linearly
slidable slide plate 18 is provided in its one end with respect to
the sliding direction with the powder supply port 19, and is
provided at the other end opposite of the mask frame 40 with a
suction nozzle 185 for sucking the powder. The suction nozzle 185
is slidable along a slit 184 which is formed at the other end to
extend in a direction perpendicular to the sliding direction, and
is moved after the sintering of the powder 8 or the grinding to a
position where the portion including the slit 184 is located above
the base 11, as shown in FIG. 17(c) so that the suction nozzle 185
is driven to slide along the slit 184 for sucking the uncured
powder or the swarf.
[0099] With the above sucking for the powder removable, it is
possible to prepare the uniform powder layer free from being
intermingled with spatters, and therefore obtain non-defective
cured layer. When utilizing the step of removing powder, the powder
supply section 15 gives a more amount of the powder at the
subsequent step of supplying the powder to form the powder
layer.
[0100] When the slide plate 18 is integrated with the powder supply
section 15, the mask frame 40, and the milling opening 39, the
plural bases 11 could be combined with the single elevator frame 12
such that the powder is supplied to one of the bases while the
sintering or grinding is made on the other base, or the sintering
is made on one of the bases 11 while the grinding is made on the
other base, which facilitates to fabricate the plural objects
simultaneously and efficiently.
[0101] When using the rotating slide plate 18, the slide plate can
afford a plurality of the powder supply sections 15, mask frames 40
and/or milling openings 39 in the peripheral area so as to be made
into a compact structure, or can be easily adapted for the above
combination of the plural bases 11 and the single elevator frame
12.
[0102] Although the optical unit 2 is disposed on the side of the
milling unit 3 in the above illustrated embodiment and
modifications, the optical unit 2 may be disposed on the side of
the mask frame 40 (slide plate 18), as shown in FIG. 7.
[0103] Further, when the optical unit 2 is detachable to the
headstock 31 of the milling unit 3, a mount 31 detachably mounting
the optical unit 2 is preferred to have a capability of changing
the mounting position of the optical unit 2 along the vertical
direction, as shown in FIG. 18.
[0104] As the mounting level of the optical unit 2 is higher, the
longer the distance to the working surface so that the same scan
angle of the scan mechanism 22 results in a longer scan path than
in the shorter distance to the working surface with a resulting
increased scanning rate. However, an error in the scan angle would
result in an increased positional error on the working surface.
[0105] Accordingly, when the rapid scanning is required to cover a
wide range for the lamination object not requiring high precision,
the optical unit 2 can be mounted at a relatively high level to
assure rapid formation of the cured layer, while the optical unit 2
can be mounted at a relatively low level when the high precision
scanning is required.
[0106] Further, it is possible to select the low mounting level
when the optical unit 2 irradiates the light beam L to the
outermost part of the object, and select the high mounting level
when the optical unit 2 irradiates the light beam L to the interior
part of the same object.
[0107] FIG. 19 illustrates a modification in which a cover 193 is
provided to close the upper opening of the powder supply port 19 in
the slide plate 18. The cover 193 is included to keep the powder 8
free from dirt or dust, the spatters developing at the sintering,
or the swarf developing at the grinding.
[0108] Preferably, the cover 193 is configured to open and close in
synchronous with the sliding movement of the slide plate 18. The
rotatably supported cover 193 shown in FIG. 20 is caused to rotate
when abutting against a stopper 194, and open the upper opening of
the powder supply port 19.
[0109] FIG. 21 illustrates a modification in which the elevator
frame 12 is provided with a discharge port 125 for discharging
residual powder 8 remaining on the top face of the elevator frame
12. Only a minimum clearance is left between the elevator frame 12
and the slide plate 18 such that the powder, the swarf, or the
spatters accumulating on the base 11 to rise above the top face of
the elevator frame 12 are squeezed towards the periphery of the top
end of the elevator frame 12 as the slide plate 18 slides.
[0110] The discharge port 125 acts to discharge the powder and the
swarf without interfering with the sliding movement of the slide
plate 18. The discharged powder 8 can be collected through a sieve
for re-use.
* * * * *